Differential froth flotation of sulfide ores



Sept. 28, 1948. H. L. GIBBs 2,449,984

DIFFERENTILFROTH FLOTATION OF SULFIDE ORES Filed Aril 1o, 1944 Patented Sept.. 28, i 1948 UNITEDl STATES PATENT OFFICE om FLo'rA'rroN or ULFIDE oars y Harold L. Gibbs, 'Salt Lake City, Utah i Application April 10, 1944, Serial No. 530,389

DIFFERENTISAL rn 23 Claims. 1

This invention relates to a process of flotation for separating metalliferous sulphides one from another and from other minerals by which they may be accompanied, especially in the case of ore minerals and concentrates. Quite particularly, the process relates to froth flotation, and to the concentration of metalliferous sulphides such as Primarily, among the important objects of the invention are the following:

An improvement in the separation of molybdenlte from other sulphides principally copper and iron.

An improvement in agents by means of which the separation of certain metalliferous sulphides from otherminerals is greatly facilitated.

An improvement that-makes it possible to control the separation of molybdenite from other sulphides.

Other objects will appear when the process is fully understood.-

In processes of flotation it is usual to float more than one mineral in the initial or rougher stage. In the flotation' process of the invention, it is a distinctive feature to obtain a separation of these minerals by preventing the flotation of a particular mineral either in the initial flotation step or in a subsequent step.

The flotation of minerals in an aqueous pulp fundamentally depends upon the extent of water wetting or non-wetting of the mineral particles which it is desired to separate from other mineral particles. Thus in separating molybdenite from copper or iron sulphides, the purpose is to encourage the floating of the molybdenite by nonwetting the surfaces of the particles and to depress or inhibit the floating of the copper and iron sulphides by wetting the surfaces of those particles. It is to this latter purpose that the use of the novel agents of this invention are directed. By using well known agents to increase the floatability of a particular metalliferous` sulphide and using the novel agents of the invention to depress certain other metalliferous sulphides, the process of the invention can be so adjusted that various metalliferous sulphides are profitably separated one from another.

I have discovered a particular group of organic compounds each of the members of which acts 2 very energetically to depress or prevent the flotation of couper sulphides and other sulphide minerals while at the same time allowing the ilotation of molybdenite. This group of organic agents has thetype formula HSRCOOH or a. very similar type formula HSRCOSH, in both of which R represents an organic group, advantageously and for example, a saturated aliphatic group otherwise known as a saturated straight chain.

Various examples of chemical compounds under the type formula may be given as follows:

Si) Hs R Coon 'r formula 2) BIS` CH: COOH T cglycollic acid (3) HS COOH Alpha mercapto butyric acid z CH3 (4) HS COOH Alphamercapto caproic acid i CE1 CH2 CH: (5) KS (03 COSK Potassium dithio oxalate The type formula HSRCOOH is intended to include also the water soluble salts of these acids which may be formed either during their preparation or after being placed in the flotation pulp, because of the positive ions in the pulp. A particular example -of this formation is in the agent potassium dithio oxalate, KSOCCOSK, where the 4potassium ion has replaced the hydrogen io'n, also in mercapto caproic acid which was converted to the sodium s alt before being used.

In applying the invention the depressing properties of thioglycollic acid on copper sulphide minerals have been investigated over a wide range of pH values including both acid and alkaline values. The value of pH is not a limiting factor at pH values lower than 9. Above a 9 fpH the results become progressively poorer. As there is such a wide range of pH values at which this compound is effective as a depressant, the type-of ore and previous treatment, as well as the particular depressant used, plays a part in establishing the optimum pH value.

The depression of copper sulphide minerals by thioglycollic acidis illustrated in the various examples which will follow presently.

A flotation concentrate to which the process of the invention has'been applied with favorable results, is one produced by the Utah Copper Com- Dany. This particular concentrate consists mostly of copper sulphide minerals accompanied by a small-percentage of molybdenite. As a rule the Utah Copper-Company concentrate' assays approximately 33 per cent copper and one per cent molybdenite, the flotation being accomplished by means of the usual agents, burner oil and an alcohol frother.

In two examples of using the process of the A invention on Utah Copper Company concentrates,

the tendency of the copper sulphide minerals to float with the molybdenite was successfully over- The pro- Insol. Mos,

vPer Cent Distribution Cu l Insoi. MOS;

urner Oil wenn meme Insol. MOS,

met meen Alpha Mercapto Butyric Acid man@ mena MOS:

113301. Moss Per CentAssays Insel. MoSz Per Cent Distribution Per Cent Distribution Per Cent Weight Examples of the use of the other novel agents Example No.

Flotatlon agents in pounds per ton were added Moss Hammam ruimen from 1.49 per cent to '15.00 per cent. gressive elimination of copper due to the depressing action of thioglycollic acid is clearly shown.

Imi.

which satisfy the type formula, follow as follows Insol.

wmmmmw lease Assay, Per Cent Per Cent Assays yiJu 3.0 lbs.

@sont Per Cent Weight Per Cent Weight Iusol.

Per Cent Assays Per Cent Weight In this example it is shown that. alpha mercapto butyric acid depresses 85.10 percent of the cop- Eample No. 4-

60 per sulphides, while at the same time only `4.83 per cent of the molybdenite is prevented from floating.

Example No. 1

g (otation concentrate). ertailing...-

Example No. 2

' Cleaner tailing Molybdenite concentrate....-

(dotation concentrate) pper concentrate not floated.. Molybdenite concentrate iioeted.

In this example 96.96 fper cent of the copper was depressed, while 95.06 of the molybdenite Headin Rough come by the depressive action of thioglyoollic acid while the mclybdenite was unailected and was oated ywith the usual collector agents. The two examples are recorded as follows was floated. `lotation agents used were tmogwcuc ma, 0.6 1b. turner an. 0.2 1b. 13 22 frother per ton. l

collic acid Oil Conc. Thio ly- Burner Resultin HSO Lime g B 22 g 55 In this example flotation agents in pounds per tons were added as follows Also in .this example, several cleaning operations were made raising the per cent molybdenite Roufherm... lst c eenen.-. 2nd cleaner-.. 3rd c1eaner..

Molybdenite concentrate .notation agents in pounds per ton were added as follows:

cresylie acid. 25 per cent amyl alcohol No. 44, 25 percent B-22 frother) per ton oi' ore.

In the first test, i. e. where thioglycollic acid .upm l was not added the xanthate floated 30.85 per4 cent lvrgw 3,22 Blger DE 5 of the iron, while in the second test,'i. e. where xc thioglycollic acid was added, only 5.54 per cent of the iron iloated. non mailing 1.1 0.08 0.0 8.45 Exam le No. 8 cleaimnumg 1.1 0.34 0.0 aa. p 10 Per Cont eigtgg' 1 Neutralized with sodium hydroxide solution. Per Cent Assays on In this example it was found that the alpha might mercapto caproic acid was largely insoluble in cu Fe Fe the flotation pulp, so that it was necessary to convert it into the sodium salt by reacting the acid -Hwmi Hmmm id 00 no o 50o 135 100 00 -with sodium hydroxide. The pronounced froth- Rgugh--j:1:: 94:77 1 70 69:15 ing properties of this compound limited the quan- Rougner concentrate s. 23 13.15 30.85 tity that could be used, butin spite of the limita- Wm, n 6 lh TM oglycollic tions the test shows the characteristic depressive Acid perron action of substances coming under the type for- Rougherfraumg 33 2 1, 94.4 1111118.. Rougher Concentrate 2.67 4.70 5.54

Example No. 5

Per Cent Assays Per Cent Distribution Per Cent.

Weight Cu Insol. M081 Cu Insel. MOS

Heading (notation concentrate' 100.00 44. 950 4.40 1.50 100.00 100.00 100.00 Rougher telling 91.50 42. 250 4.00 0.14 94.53 82.36 7. 48. oleanerzau 5.32 34.000 8.40 8.20 4.24 10.06 25.48 Molybdente concentrate... 3.18 16.950 10.60 35.10 1.23 7.58 07.04

Flotation agents in pounds per ton were added as follows:

This example shows potassium dithio oxalate to have an effective depressive action upon copper sulphide minerals and gives further proof as to the reliability of the type formula.

These .examples indicate that the novel depressants of the invention are effective with lead and zinc sulphides. The lead and zinc concentrates used in these tests were obtained by a well known method of flotation. In each case the novel depressants were added separately to the concentrate to depress the lead and zinc. Example 6 shows the percentage of `lead and zinc floated bythe wellknown method of flotation and Example 7 the percentage of lead and zinc depressed by my novel depressants.

Example No. 6

Another example, numbered 8 which follows, represents two tests made relative to an ore containing a considerable amount of pyrite. Both the tests included in Example 8 were made under similar conditions, the dierence `in the two being that in the first test no thioglycollic acid In the accompanying drawing, which illustrates an instance of applying the process of the was used, while in the second test' thioglycollic acid was added after the pulp was agitated in thepresence of ethyl xanthate. Flotation agents common to =both tests include 3.25 lbs. lime, 0.1 lb. ethyl xanthate, 0.33 lb. frother (50 per cent invention to actual practice, the single figure is a flow diagram representing a. flotation plant using the novel process of the invention.

Referring to the. drawing, the numeral l0 indicates a feed of aqueous flotation pulp consisting of molybdenite and copper sulphide minerals, the feed containing approximately 33 per cent Cu and one per cent MoSz.- The feed enters the flotation circuit at 26, is acid conditioned at 21, and lime conditioned at 20. Farther on, for example at 29, a novel depressant agent is added after which the pulp at 30 enters the flotation section 3|,` the molybdenite concentrate (float) being discharged at 32 while the copper concentrate (sink) is discharged at 3 4.

Briefly summarizing comparatively, the prior and new'practices in treating Utah Copper Company flotation concentrate to separate the molybdenite from the copper sulphide minerals, it may bestated that the prior practice comprises two general steps. 'I'he first step involves the use of dextrine to prevent the flotation of the molybdenite while a portion of the copper. minerals are removed vasa froth. The second step involves the further raising in grade-of theflotation tai-ling or low grade 'molybdenite concentrate by heating sufficiently to alter the surfaces of the copper minerals and render them unfloa-table. fter'which the molybdenite is floated away from the copper minerals. As opposed to that procedure, the new practice according to the invention, comprises first conditioning the original flotation concentrate with acid and then with lime, followed by the addition to the flotation pulp of a novel flotation agent which causes the copper minerals to be depressed, whereupon the molybdenite is floated away from the copper minerals. Thus the new procedure eliminates one flotation step and the necessity of providing the heat-treating equipment.

The disclosure herein, though embodying 7 specific examples, is limited only by the following claims.

What I claim is:

1. In a prg/cess of notation for the separation fbi. metalliferous sulphides, the step lof agitating and aerating an aqueous pulp containing said metalliferous sulphides, in the presence of a i'rothing and a collecting agent for one of the sulphides and, further, in the presence of a depressant selected fromlthe group of compounds -having the formula HS-R-COOH. wherein R is an organic radical.

2. In a process of flotation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the step of agitating and.

aerating an aqueous pulp containing the same, in the presence of a frothing and a collecting agent for the molybdenite and, further, ixr the presence of a depressant selected from the group of compounds having the formula HS--R-COOH wherein R is an organic radical.

3. In a process of flotation for the separation of metalliferous sulphides, the steps of, ilrst, subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning suiiicient to bring the pulp to an alkaline state, and, third, subjecting the so `conditioned pulp to agitation and aeration in the presence of afrothing and a collecting agent for one of the sulphides and, further, in the presence of adepressant selected from 'the group oi' compounds having the formula HS-R-COOH wherein R is an organic radical.

4. In a process of ilotation for the separation oi" molybdenite from copper, iron, and similar sulphide minerals, the steps of, rst, subjecting an aqueous pulp containing the -said Imetalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning suilicient to bring the pulp to an alkaline state, and, third, subjecting the so conditioned pulp to agitation and aeration in the presence of a frothing anda collecting agent for the molybdenite and, further, in the presence o! a depressant selected from the group o f compounds having the formula HS-R-COOH. wherein R is an organicradical.

5. In a process of flotation for the separation of metalliferous sulphides, the step of agitating and aerating an aqueous pulp containing said metalliferous sulphides, in the presence of a frothing and collecting agentfor one of the sulphides and, further, in the presence of a. depressant having the general formula HS-R-X, in which R isan organic radical and X is selected from the group, carbonylic radical and thiocarof'fiotation for the lseparation I rrothing and a collecting agent for one of the sulphides and. further, in the presence of potassium dithio oxalate (KSOCCOSK) 8. In a' process of flotation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the step of agitating and aerating an aqueous pulp containing the same, in the presence of a frothing and a collecting agent for the molybdenite and, further, in the presence of a depressant vselected from the group ofv compounds having the' formula HS-R-COSH, wherein R is an organic radical.

9. In a process of flotation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the step of` agitating and aerating an aqueous pulp containing the same. in the presence of a frothing and a collecting agent for the molybdenite and, further, in the presence of potassium dithio oxalate (KSOCCOSK).

10. In a process of otation for the separation of metalliferous sulphides, the steps of iirst, subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning sufficient to bring the pulp to an alkaline state, and, third, subjecting the so conditioned pulp to agitation and aeration in the presence of a frothing and a collecting agent for one of thesulphides and, further, in the presence of a depressant selected from the group of compounds having the formula HS-R-COSH, wherein R is an organic radical.

11. In a process of flotation for the separation of metalliferous sulphides, the steps of. ilrstf, subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning sumcient tobring the pulp to an alkaline state, and third, subjecting the so conditioned'pulp to agitation and aeration in the presence of a frothing and a collecting agent for one of the sulphides and, further, in the presence of potassium dithio oxalate (KSOCCOSK).

12. In a process of flotation for vthe separation v of molybdenite from copper, iron, and similar sulphide minerals, the steps of, rst, subjecting y an aqueous pulp containing the said metalliferous sulphidesl to inorganic acid conditioning-second, subjecting the acid conditioned pulp to lime conditioning suiiicient to' bring the pulp to an alkaline state, and, third, subjecting the'so conditioned pulp to agitation and aeration in the presence of a frothing and a collecting agent for the molybdenite and, further, in the presence of a depressant selected from the group of `compounds having the formula HS-R-COSH, wherein R is an organic radical.

13. In a process of iiotation for the separation of molybdenite from copper, iron, and similar l sulphide minerals, the steps of, rst, subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to'lime conditioning suilicient tofbring-thefpulp to an alkaline state, and, third, subjecting the so conditioned pulp to vagitation and aeration in the presence of a frothing` anda collecting agent for the molybdenite and, further, in the presence of po tassium dithio oxalate (KSOCCOSK). I

14.- In a process of notation for the separation of metalliie'rous sulphides, the step of agitating f and aeratingy an aqueous pulp containing said v mercapto butyric acid (HSCaHeCOOH) as a depressant.

16. In a process of notation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the step of agitating and aerating an aqueous pulp containing the same, in

-the presence of a frothing and a collecting agentfor the molybdenite and. further, in the presence of thioglycollic acid (HSCHzCOOH) as a depressant.

17. In a process of ilotation for the separation of molybdenite from copper,iron, and similar sulphide minerals, the step of agitating and aerating an aqueous pulp containing the same, in the presence'of a frothing and a collecting agent for the molybdenite and, further, in the presence of alpha mercapto butyric acid (HSCsHeCOOH) as a depressant.

18. In a process of iiotation for the separation of metalliferous sulphides, the `steps of, first, subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning sufficient to bring the pulp to an alkaline state, and, third, subjecting -the* so conditioned pulp to agitation and aeration in the presence of a i'rothing and a collecting agent for one of the sulphides and, further, in the presence of thioglycollic acid (HSCI-IzCOOI-I)I as a depressant.

19. In a process of ilotation for the separation of metalliferous sulphides, the steps of, rst, subjecting an aqueous pulp con-taining the' said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning suiiicient to bring the pulp to an alkaline state, and, third, subjecting the so conditionedpulp to agitation and aeration in the presence of a frothing and a collecting agent for one of the sulphides and, further, in the presence of alpha mercapto butyric acid (HSCsHaCOOH) as a depressant.

20. In a process of dotation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the steps of, iirst. subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime con- 10 ditioning suiiicient to bring the pulp to an a1- kaline state, and, third, subjecting the so conditioned pulp to agitation and aeration in the presence of a frothing and a collecting agent for the molybdenite and, fur-ther, in the presence of thioglycollic acid (HSCHzCOOH) as a depressant.

2l. In a process of flotation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the steps of, iirst, subjecting an aqueous pulp containing the said metalliferous sulphides to inorganic acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning suilicient to bring the pulp to an alkaline state, and, third, subjecting the so conditioned pulp to agitation and aeration in the presence of a frothing and a collecting agent for the molybdenite and, further, in the presence of alpha mercapto butyric acid (HSCsHeCOOH) as a depressant.

22. In a process of flotation for the separation of metalliferous sulphides, the steps of, first, subjecting an aqueous pulp containing the said metalliferous sulphides to concentrated sulphuric acid conditioning, second, subjecting the acid conditioned pulp to lime conditioning sufiicient to bring the pulp to an alkaline state, and, third, subjecting thefso conditioned pulp to agitation and aeration in the presence of a irothing and va collecting agent for one of the sulphides and, iurther, in the presence of thioglycollic acid (HSCHzCOOH) as a' depressant.

23. In a process of notation for the separation of molybdenite from copper, iron, and similar sulphide minerals, the steps of, first, subjecting an aqueous pulp containing the said metalliferous sulphides to concentrated sulphuric acid conditioning, second, subjecting the acid conditioned v pulp to lime conditioning suicient to bring the pulp to an alkaline state, and, third, subjecting the so conditioned pulp to agitation and aeration in the presence of a frothing and a collecting agent for the molybdenite and. further, in the presence of thioglycollic acid (HSCHaCOOH) as a depressant.

HAROLD L. GIBBS.

REFERENCES CITED The followingv references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,070,076. Brown Feb. 9. 1937 2,095,967 Brown Oct. 19. 1937 2,187,930 

